class WorkerThread extends Thread {
    @Override
    public void run() {
        while (true){
            System.out.println("打螺丝");
        }
    }
}

public class Test1 {
    public static void main(String[] args) {
          WorkerThread worker = new WorkerThread();
          worker.run();   // 直接调用run
          //worker.start();    // 调用 start() , 雇佣别人来打螺丝
          while (true){
              System.out.println("我是监工,不打螺丝");   //  我是main主线程,不打螺丝 ;
          }
    }
}
